Rotary piston and seal therefor



1967 KENICHI YAMAMOTO ET AL ROTARY PISTON AND SEAL THEREFOR 3Sheets-Sheet '1 Filed Feb. 18, 1965 Ken/chi Yamamafo Sunao Osakada MM, Mz/WM ATTORN Evs Jan. 24, 1967 KENICHI YAMAMOTO ET 3,300,127

ROTARY PISTON AND SEAL THEREFOR Filed Feb. 18, 1965 3 Sheets-Sheet 2Ken/chi Yamamoro .Sunao Osakaa'a INVENTORS ATTORNEYS 1967 KENICHIYAMAMOTO ET AL 3,300,127

ROTARY PISTON AND SEAL THEREFOR Filed Feb. 18, 1965 3 Sheets-Sheet 5Ken/chi Yamamoro Sunao Osakada INVENTORS BY M MMZ, ZMWA ATTORNEYS UnitedStates Patent O 3,300,127 ROTARY PESTON AND SEAL THEREFOR KeniciiiYamamoto and Sunao Osakada, both of Hiroshirna-shi, Japan, assignors toToyo Kogyo Company Limited, Hiroshima-ken, Japan Filed Feb. 18. 1965,Ser. No. 433,584 (Ilaims priority, application Japan Feb. 26. 1964, 39/11,814, 3/14.815; Feb. 28, 1964, 39/10,930 9 Claims. (Cl. 230-145) Thepresent invention relates to a rotary piston internal combustion engineand particularly to a sealing device for forming a seal between a rotarypiston and the end walls of the casing of the engine.

A rotary piston internal combustion engine generally consists of anannular casing having a trochoid-shaped internal peripheral wall and endwalls on the opposite ends of the annular casing, which end walls haveflat internal faces. A triangular rotary piston is rotatably mounted ona crank pin which is eccentrically mounted on a crankshaft which extendsthrough the center of the combustion chamber defined by the annularcasing and the two end Walls. At each apex of the rotary piston is asealing member which forms a sealbetween the rotary piston and theannular casing and defining combustion chambers between the triangularpiston and the trochoidshaped internal Wall of the annular casing. Onthe fiat end face of the triangular piston adjacent the outer edge ofthe piston is also a sealing member forming a seal between the rotarypiston and the end walls of the casing. Cooling of the rotary pistonduring the operation of the above described engine is carried out bysupplying cooling oil through apertures provided around the crank pinwithin the rotary piston. On the flat faces of the opposite sides of thepiston, the apertures through which the cooling oil is supplied, open inthe axial direction and surrounding each of the said apertures is aninternal sealing ring which also forms a seal between the piston and theside walls of the casing'and maintains the cooling oil sealed within theapertures.

The problem in the engine of the above described type is that theleakage of explosive gas past the side seals at the outer edge of theend faces of the rotary piston is inevitable during the operation of theengine, and the inner seal ring surrounding the said cooling oilapertures is affected by the pressure of the leaking explosive gas anddeteriorates in its effectiveness as an oil seal. There have beensuggestions to install the inner sealing ring around the said coolingoil apertures with a spring means positioned behind the sealing ringwithin a circular groove on the piston end face to force the sealingring outwardly against the inner surface of the end walls of the casing,but this arrangement has proved defective for sealing off the coolingoil apertures tightly because the pressure of the leaking gas is veryhigh and the effect of the spring means behind the sealing ring isdefeated by the effect of the pressure of the leaking gas during theoperation of the engine.

It is an object of the present invention to provide a sealing device fora rotary piston engine which effects an air and oil-tight seal between arotary piston and the end walls of the casing by utilizing either gas oroil pressure applied thereto.

Another object of the present invention is to form an oil-tight sealbetween the rotary piston and the end walls of the casing by applyingthe pressure of the cooling oil for the piston which is due tocentrifugal force to the sealing ring, whereby the sealing effect isautomatically increased in proportion to the amount of the said.

centrifugal force.

and 2'.

ice

Other and further objects of the invention will become apparent from thefollowing specification and claims, taken together with the accompanyingdrawings, in which:

FIG. 1 is a cross-sectional view of a rotary piston engine showing arotary piston provided with a sealing device according to the presentinvention;

FIG. 2 is a longitudinal sectional view taken on the line 22 of FIG. 1;

FIG. 3 is a fragmentary sectional view of a portion of FIG. 2 on anenlarged scale and showing the details of the sealing unit;

FIG. 4 is a fragmentary sectional view taken on line 4-4 of FIG. 3;

FIGS. 5 and 6 are cross-sectional views similar to FIG. 3 and showingmodified forms of the sealing device of FIG. 3;

FIG. 7 is a fragmentary sectional view taken on line 7-7 of FIG. 6;

FIGS. 8 and 9 are cross-sectional and longitudinal sectional views,respectively, similar to FIGS. 1 and 2 of a rotary piston engine with amodified sealing device according to the invention;

FIGS. 10, 12 and 13 are fragmentary sectional views similar to FIG. 3and showing details of modified forms of the sealing unit of FIGS. 8 and9; and

FIGS. 11 and 14 are fragmentary sectional views taken on the lines 11-11and 1414 of FIGS. 10 and 13, respectively.

Referring first to FIGS. 1, 2, 3 and 4, a combustion chamber a isdefined within an annular casing 1 having 'an internal peripheral wallwhich is trochoid-shaped and two end walls 2 and 2 at the opposite endsof the annular casing. Positioned-within the combustion chamber a is atriangular rotary piston 3 having a plurality of apexes which are movedalong the internal peripheral wall of the center casing 1 duringrotation of the piston. At the apexes and along the peripheral side edgebetween each pair of apexes of the piston are sealing members 4 and 5.which form seals between the piston 3 and internal walls of the annularcasing 1 and the end walls 2 and 2'.

Extending through the center of the combustion chamber a is a crankshaft6 which is rotatably mounted in cylindrical crankshaft bushings 7 fixedin the end walls. Integral with the crankshaft 6 is a crank pin 8 whichis eccentrically positioned with respect to the axis of the crankshaft6, and which is rotatably positioned within a central axial bore in thepiston 3 in a bushing 9 fitted within the said central axial bore of thepiston. Extending in opposite directions from the said axial centralbore of the piston are circular apertures 10, which may be somewhatlarger in diameter than the said axial central bore and which openagainst the end walls- 2 Extending axially through the crankshaft 6 is alongitudinal bore 11 which is connected with a source of rotary pistoncooling oil (not shown) by conventional means, and branch holes 12 and13 connect the longitudinal bore 11 with apertures 10 within the piston3 to supply the cooling oil for apertures 10. Fixed in one circularaperture 10 is an internal gear 14 which meshes with an external gear 15fixed on the crankshaft bushing 7.

Surrounding apertures 10 on each end face of the piston 3 are circulargrooves 16 within which sealing rings 17 are inserted. Sealing rings 17are axially slidable within but are fixed against rotation with, respectto the circular grooves 16. Behind the sealing rings 17 within thegrooves 16 are circular recesses 19 within which are positioned circularsprings 18 urging the sealing rings 17 outwardly against the internalfaces of the end walls 2 and 2. Between ther adially inwardly facingwall of the grooves 16 and the radially outwardly facing surfaces of thesealing rings 17 are circular passages 29 through which the recesses 19behind the sealing rings are in communication with the combustionchamber a when the outer sealing members 5 permit the combustion gas toleak past the sealing members 5. In the radially outwardly facingsurface of the groove is a circular groove 21 within which is anauxiliary sealing ring 22 in tight sealing engagement between theradially inwardly facing surface of the sealing ring 17 and the bottomof the groove 21. Numeral 23 designates drain ports in the end walls 2and 2 to exhaust cooling oil from the aperture 10.

The engine is operated in the conventional manner by firing thecompressed gas compressed within the chamber a by rotation of thetriangular piston 3. Intake of combustible gas and exhausting of theproducts of combustion is carried out by means of conventional intakeand exhaust ports (not shown). Leakage of the compressed gas andproducts of combustion past the side sealing member 5 causes gas to flowalong the gap between the end face of the rotary piston 3 and end walls2 and 2' and into the circular passages 20', and thus into the circularrecesses 19. The pressure of the gas which has thus leaked past thesealing member 5 and reached the recess 19 forces the sealing rings 17against the internal face of the end walls 2 and 2, and increases thesealing effect between the rotary piston and the end walls in proportionto the pressure of the thus leaked gas. Accordingly the sealing rings 17automatically adjust the sealing effect in proportion to the pressure ofthe leaking gas which is applied thereto. And because the leaked gas isled along the passage 20 into the recess 19, concentrated action of thepressure against the contact area between the sealing ring and the endwall, which-causes deterioration of the sealing effect, is avoided.

During the operation of the engine, cooling of the rotary piston iscarried out by supplying cooling oil to the space within the aperturesprovided in the rotary piston, from a source of cooling oil (not shown)through the longitudinal bore 11 and the branch holes 12 and 13 in thecrankshaft 6. Depending on the speed of rotation of the rotary piston,the cooling oil supplied to the apertures 10 is affected by thecentrifugal force, due to the revolution of the piston 3, and is forcedradially against the circular wall of the apertures 10. This causes,during the operation of the engine, leaking of the cooling oil past thesealing rings 17. According to the present invention, the sealing effectbetween the sealing rings 17 and the end Walls of the casing isincreased in proportion to the pressure of the gas leaking from thecombustion chamber a, and the auxiliary sealing ring 22 maintains atight seal between the radially outwardly facing wall of the grooves 16and the radially inwardly facing surface of the sealing rings 17. Thusthe leaking of the cooling oil past the sealing ring 17 from theapertures 19 is also entirely prevented.

The springs 18 behind the rings 17 act to compensate the positioning ofthe rings 17 when wear occurs at the contact face between the rings 17and the end walls 2 and 2'.

FIG. 5 shows a modified form of sealing ring 17a which is similar to thesealing ring 17 of FIGS. 1-4 in that it is similarly mounted in acircular groove 16 in the end face of a rotary piston 3 such that aspace 20 is left between the radially outwardly facing face of thesealing ring 17a and the radially inwardly facing surface of the groove16 and a recess 19 is left behind the sealing ring. However, it differsfrom the sealing ring 17 in that a projecting circular lip 24 isprovided on the face of the sealing ring opposed to the internal face ofthe end walls 2 and 2' which wipes the oil leaking along the inner faceof the end wall off said face of the end wall. In addition, instead ofhaving a circular groove 21 in the radially outwardly facing surface ofthe groove 16, a circular groove 21;; is provided in the radiallyinwardly facing surface of the sealing ring 17a in which is positionedan auxiliary sealing ring 22 identical to the sealing ring 22 of theembodiments of FlGS. l-4, and which functions in the same way. Thefunction of the embodiment of FlG. 5 is the same as that of FIGS, 1-4.

FIGS. 6 and 7 show a modified form of the invention in which structureof the casing, rotor, etc., are the same as in the embodiment of FIGS.14, but in which the sealing ring is modified so that the circularpassages 29 are provided between the radially outwardly facing wall ofthe grooves 16 and the radially inwardly facing surface of the sealingrings 171 so that the circular recesses 19 are in communication with theapertures 10. The cooling oil under the effect of centrifugal force,which is due to the rotation of the piston 3, is led along the passages20 and received within the recesses 1?, and the sealing rings 17]) areforced outwardly against the inner face of the end walls by the pressureof the cooling oil, and increase the sealing effect in proportion to theamount of centrifugal force. The auxiliary sealing rings 22b in thismodified form are positioned within circular grooves 21b provided on theradially outwardly facing circumferential surf-ace of the sealing rings17b and maintain a tight seal between the sealing rings 17b and theradially inwardly facing circular wall of the grooves 16. The groove andauxiliary sealing ring can also be provided in the radially inwardlyfacing wall of the groove 16.

FIGS. 8, 9, 10 and 11 show a further modified form of the invention, inwhich the piston 3 in a motor the same as that shown in FIGS. 1 and 2has, in addition to the inner circular grooves 16 which surround theapertures 1t} and which are provided on both end faces of the piston 3,additional outer circular grooves 16 which are positioned radiallyoutwardly of grooves 16 surround the grooves 16. The sealing ring isprovided in the radially inwardly positioned groove and is ar ranged ina manner similar to the embodiment of FIGS. 6 and 7 so that a circularpassage 20 is left between radially outwardly facing wall of the grooves16 and the radially inwardly facing surface of the sealing rings 17c,and the sealing ring 17c is provided in the outer groove and is arrangedin a manner similar to embodiment of FIGS. 3 and 4 so that a passage 2%is left between the radially inwardly facing wall of the groove 16 andthe radially outwardly facing surface of the sealing ring 17c. Thus therecesses 19 behind the sealing rings 170 are connected with theapertures 10 in the piston 3, and the recesses 19 behind the sealingrings 170 are connected with the combustion chamber a through the gapbetween the outer sealing members 5 and the inner surface of walls 2 and2 during operation of the engine. During the operation of this modifiedembodi ment, the cooling oil under the effect of centrifugal force isled along the circular passages 21) from the apertures 10 in the piston3 and into the recesses 19, and at the same time the gas leaking fromthe combustion chamber past the outer sealing member 5 is led along thecircular passages 20 and into the recesses 19, and the sealing effect ofsealing rings 17c and 170 is increased with the increasing pressureapplied thereto as the speed of the engine increases. If the cooling oilshould leak past the rings 17c, it will be blocked by the outer sealingrings 17c, and if the gas from the chamber a should leak past the outersealing ring 17c, it will be blocked by the inner sealing ring 17c, sothat the seal between the piston and the end walls is complete. Theauxiliary seal rings 22 are positioned within the grooves 21c providedon the radially outwardly facing circumferential face of the innersealing rings 17c and effect sealing between the inner sealing rings 17cand the radially inwardly facing circular wall of the grooves 16 similarto the embodiment of FIG. 6. Additional auxiliary sealing rings 22 arepositioned within the grooves 210' provided on the radially inwardlyfacing circumferential face of the outer sealing rings 17c and likewiseeffect sealing between the outer sealing ring 170' and the radiallyoutwardly facing circular wall of the grooves 16. The sealing rings 17cand 170 are maintained in contact with the inner face of the end wallsby means of springs 18 and 18' installed behind the sealing rings.

FIG. 12 shows a modified form of the sealing rings 17d and 17d which areeach provided with a projecting circular lip 24d and 24d respectively atthe point Where they contact the inner face of the end wall, whereby theoil leaking along the inner face of the end walls is scraped off by theprojecting lips 24d and 24d. FIGS. 13 and 14 also show a modified formof the sealing unit similar to the embodiment of FIG. 4 and in which theauxiliary seal rings 22 and 22' are installed within circular grooves212 and 21e' which are provided in the walls of the grooves 16 and 16'and form a seal between the wall of the grooves and the sealing rings.

What is claimed is:

1. A rotary piston and sealing means for a rotary piston internalcombustion engine having an annular casing with a trochoidal shapedinternal peripheral wall and a crankshaft within said casing foreccentrically rotating a rotary piston Within the casing, and thecrankshaft having cooling oil bores therethrough for supplying coolingoil to a rotary piston, and the casing having end walls on the endsthereof with substantially flat internal faces, said rotary piston andsealing means comprising a triangular shaped rotary piston havingsubstantially flat end faces adapted to be eccentrically mounted on thecrankshaft for rotation within the annular casing, sealing means at theapexes of said rotary piston and along the outer edges of the piston endfaces adapted to seal against the internal peripheral wall of theannular casing and the flat internal face-s of the end walls for sealingoff the combustion chambers and compressing chambers from the spacebetween the end faces of the piston and the end walls, said pistonhaving annular chambers around the crankshaft and opening out of each ofthe end faces of the piston and adapted to receive cooling oil from thebores in the crankshaft, and said piston having two circular grooves ineach end face intermediate the annular oil chamber and the sealingmeans, said grooves each being defined by opposed radially facingsurfaces and a laterally facing bottom surface, a sealing ring in eachsaid circular groove, the sealing ring in the outermost circular groovebeing in sealing engagement with the outwardly radially facing surfaceof said groove and being spaced from the inwardly radially facingsurface and bottom surface of said outermost groove, and the sealingring in the innermost circular groove being in sealing engagement withthe inwardly radially facing surface of said groove and being spacedfrom the outwardly radially facing surface and bottom surface of saidinnermost groove, and spring means in each of the spaces between thecircular sealing rings and the bottom surfaces of said grooves andurging said rings out of said grooves against the internal face of theend wall adjacent the end face of the piston.

2. A rotary piston and sealing means as claimed in claim 1 in whichthere is an auxiliary groove in one of the radially facing surfaces ofeach of the sealing rings and grooves which are in sealing engagement,and an auxiliary sealing ring in each auxiliary groove for providing thesealing engagement between the groove face and the sealing ring face.

3. A rotary piston and sealing means as claimed in claim 2 in which theauxiliary grooves are in the sealing r1ngs.

4. A rotary piston and sealing means as claimed in claim 2 in which theauxiliary grooves are in the radially facing surfaces of the grooves.

5. A rotary piston and sealing means as claimed in claim 1 in which eachsealing ring has a projection on the face thereof opposed to theinternal face of the end wall for engagement With the end wall.

6. A rotary piston and oil sealing means for a rotary piston internalcombustion engine having an annular casing with a tro'choidal shapedinternal peripheral wall; a crankshaft rotatably supported within saidcasing and having a crank pin portion located in the said casing; saidcrankshaft having cooling oil bores therethrough for supplying coolingoil to a rotary piston; a triangular rotary piston having substantiallyfiat end faces and eccentrically rotatably journaled on the said crankpin portion; sealing means at the apexes of said rotary piston and alongthe outer edges of the piston end faces sealingly defining workingchambers between the casing and the rotary piston; and said rotarypiston having annular chambers around the crankshaft and opening out ofeach of the end faces of the piston and into which said oil bores opento receive cooling oil from said bores; said rotary piston and oil sealmeans comprising at least one circular groove in each end face of therotary piston intermediate the annular cooling oil chamber and thesealing means; each circular groove being defined by spaced opposedradial/1y facing surfaces which are parallel and coaxial and a laterallyfacing bottom surface; a wear-resistant and substantially rectangularcross-section metal oil seal ring axially slidably inserted within eachof the said circular grooves; a wave spring means disposed in the spacebetween each sealing ring and the bottom face of the groove so that thesaid sealing ring is urged axially out of the groove and resiliently andsealingly engaged with the internal face of the end wall; and saidsealing ring being in sealing engagement with the radially inwardlyfacing surface of said circular groove and spaced from the radiallyoutwardly facing surface of said groove and from the bottom surface ofthe groove, whereby cooling oil under pressure can pass between thesealing ring and the radially outwardly facing surface of said circulargroove and act on the sealing ring in combination with the said wavespring to urge it against the inner face of the end wall so that thesealing effect is increased responsive to the oil pressure appliedthereto; one of the radially facing surfaces of the sealing ring andtheg roove which are in sealing engagement having an auxiliary annulargroove therein; and an auxiliary sealing ring in each auxiliary annulargroove for assuring sealing engagement of the radially inwardly facingsurface of the circular groove with the sealing ring.

7. A rotary piston and oil sealing means as claimed in claim 6 in whichthe auxiliary annular groove is in the radially outwardly facing surfaceof the sealing ring.

8. A rotary piston and oil sealing means as claimed in claim 6 in whichthe auxiiiary annular groove is in the radially inwardly facing surfaceof the groove.

9. A rotary piston and oil sealing means as claimed in claim 6 in whichthe sealing ring has a projection on the face thereof opposed to theinternal face of the end wall for engagement wit-h the end wall.

References Cited by the Examiner UNITED STATES PATENTS 3,134,600 5/1964Fisch 1238 3,165,259 1/1965 Muller et al 1238 3,171,590 3/1965 Bente leet al 123-8 3,179,331 4/1965 Paschke et a1. t230- 3,180,563 4/1965 Joneset a1 23O145 FOREIGN PATENTS 939,189 10/1963 Great Britain.

DONLEY J. STOCKING, Primary Exa miner.

WILBUR J. GOODLIN, Examiner.

1. A ROTARY PISTON AND SEALING MEANS FOR A ROTARY PISTON INTERNALCOMBUSTION ENGINE HAVING AN ANNULAR CASING WITH A TROCHOIDAL SHAPEDINTERNAL PERIPHERAL WALL AND A CRANKSHAFT WITHIN SAID CASING FORECCENTRICALLY ROTATING A ROTARY PISTON WITHIN THE CASING, AND THECRANKSHAFT HAVING COOLING OIL BORES THERETHROUGH FOR SUPPLYING COOLINGOIL TO A ROTARY PISTON, AND THE CASING HAVING END WALLS ON THE ENDSTHEREOF WITH SUBSTANTIALLY FLAT INTERNAL FACES, SAID ROTARY PISTON ANDSEALING MEANS COMPRISING A TRIANGULAR SHAPED ROTARY PISTON HAVINGSUBSTANTIALLY FLAT END FACES ADAPTED TO BE ECCENTRICALLY MOUNTED ON THECRANKSHAFT FOR ROTATION WITHIN THE ANNULAR CASING, SEALING MEANS AT THEAPEXES OF SAID ROTARY PISTON AND ALONG THE OUTER EDGES OF THE PISTON ENDFACES ADAPTED TO SEAL AGAINST THE INTERNAL PERIPHERAL WALL OF THEANNULAR CASING AND THE FLAT INTERNAL FACES OF THE END WALLS FOR SEALINGOFF THE COMBUSTION CHAMBERS AND COMPRESSING CHAMBERS FROM THE SPACEBETWEEN THE END FACES OF THE PISTON AND THE END WALLS, SAID PISTONHAVING ANNULAR CHAMBERS AROUND THE CRANKSHAFT AND OPENING OUT OF EACH OFTHE END FACES OF THE PISTON AND ADAPTED TO RECEIVE COOLING OIL FROM THEBORES IN THE CRANKSHAFT, AND SAID PISTON HAVING TWO CIRCULAR GROOVES INEND FACE INTERMEDIATE THE ANNULAR OIL CHAMBER AND THE SEALING MEANS,SAID GROOVES EACH BEING DEFINED BY OPPOSED RADIALLY FACING SURFACES ANDLATERALLY FACING BOTTOM SURFACE, A SEALING RING IN EACH SAID CIRCULARGROOVE, THE SEALING RING IN THE OUTERMOST CIRCULAR GROOVE BEING INSEALING ENGAGEMENT WITH THE OUTWARDLY RADIALLY FACING SURFACE OF SAIDGROOVE AND BEING SPACED FROM THE INWARDLY RADIALLY FACING SURFACE ANDBOTTOM SURFACE OF SAID OUTERMOST GROOVE, AND THE SEALING RING IN THEINNERMOST CIRCULAR GROOVE BEING IN SEALING ENGAGEMENT WITH THE INWARDLYRADIALLY FACING SURFACE OF SAID GROOVE AND BEING SPACED FROM THEOUTWARDLY RADIALLY FACING SURFACE AND BOTTOM SURFACE OF SAID INNERMOSTGROOVE, AND SPRING MEANS IN EACH OF THE SPACES BETWEEN THE CIRCULARSEALING RINGS AND THE BOTTOM SURFACES OF SAID GROOVES AND URGING SAIDRINGS OUT OF SAID GROOVES AGAINST THE INTERNAL FACE OF THE END WALLADJACENT THE END FACE OF THE PISTON.